My driver's seat slide actuator miscounts revolutions on the slide axis, but I don't know if its miscounting going forward or reverse. It screws up the autopositioning feature. So I am going to pull the seat and disassemble the actuator.
Reading the FSM, it says to remove both battery cables first (a safety first for idiots step). Later it has you move the seat forward or back to gain access to the mounting bolts. Then later it says to remove the negative cable.
Considering the seat has side airbags, is it really necessary to disconnect the battery before disconnecting the wire harness?
Once I get it back together, will I have to do anything other than run the seat full forward and full back to reset the position count?
Any other hints appreciated.
Resolved: F50 driver's seat removal for autoposition errors
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djwarner
- Posts: 407
- Joined: Sat Jan 23, 2010 6:07 pm
- Car: 1971 240Z Series I
2006 350Z - Location: Central Florida
Re: Resolved: F50 driver's seat removal for autoposition err
I followed elwesso's advice. left the battery connected until I had removed all four mounting bolts.
Thought before starting I would go down to the local parts store and read any codes before starting. I bought the car in January with 47K and just turned 60K. The old girl didn't throw any codes for a nice surprise.
Once I got the seat out and laid on its side, I decided to remove the slave jackscrew/mounting rail first so I could remove the flexible cable at the rear of the drive motor. That proved considerably easier than removing the powered screw/rail. With that rail off, I was able to partially disassemble the servo.
It turns out the the position sensor is a reed switch actuated by a ring magnet attacheded to the jackscrew shaft. The magnet is polarized N at 12 oclock and S at 6. As the screw rotates, the reed switch opens and closed twice per revolution.
The drive had been making a grinding noise as it moved - not objectionable, but noticable when compared to the passenger side. When I removed the outer housing and motor, I found what I expected - the ring magnet was snapped in two. The magnet had two lugs that nested into two slots in the worm gear. The magnet broke at the tabs but both breaks were on the same side. The broken piece lifted out quite easily leaving both tabs attached on the other half and still engaged in the worm gear.
I decided to open up the slave jackscrew assembly to see if it also had magnet I could swap out. No luck, it just had a plastic spacer. I also confirmed that the passenger side jack screw assembly didn't have a reed switch. I then tried to disassemble one of the lift/tilt servo assemblies only to find it had a different diameter worm gear and magnet.
About this time I figured that I'd just have to reassemble everything until I could find some replacement parts in a salvage yard. When it came to putting the jackscrew assembly together, I decided to leave the broken portion of the magnet out. At least it would get one pulse per revolution.
As I was putting things back together, I noted that I could have disassembled the jackscrew servo without removing the seat by simply removing the three screws that bolted the drive assembly to the jackscrew. This would come in handy when I got the replacement parts.
After putting everything back, I powered back up and reset the settings. The seat moved in all directions without the grinding and even memorized the #1 drivers position. But when I removed the key, the seat and steering wheel did not retract. It was getting late, so I just left it that way.
This morning I ran down to Wally World to pick a newspaper and while there I set both the #1 and #2 driver position. Voila, the seat and wheel began retracting and it now doesn't drift off position with each cycle.
Thought before starting I would go down to the local parts store and read any codes before starting. I bought the car in January with 47K and just turned 60K. The old girl didn't throw any codes for a nice surprise.
Once I got the seat out and laid on its side, I decided to remove the slave jackscrew/mounting rail first so I could remove the flexible cable at the rear of the drive motor. That proved considerably easier than removing the powered screw/rail. With that rail off, I was able to partially disassemble the servo.
It turns out the the position sensor is a reed switch actuated by a ring magnet attacheded to the jackscrew shaft. The magnet is polarized N at 12 oclock and S at 6. As the screw rotates, the reed switch opens and closed twice per revolution.
The drive had been making a grinding noise as it moved - not objectionable, but noticable when compared to the passenger side. When I removed the outer housing and motor, I found what I expected - the ring magnet was snapped in two. The magnet had two lugs that nested into two slots in the worm gear. The magnet broke at the tabs but both breaks were on the same side. The broken piece lifted out quite easily leaving both tabs attached on the other half and still engaged in the worm gear.
I decided to open up the slave jackscrew assembly to see if it also had magnet I could swap out. No luck, it just had a plastic spacer. I also confirmed that the passenger side jack screw assembly didn't have a reed switch. I then tried to disassemble one of the lift/tilt servo assemblies only to find it had a different diameter worm gear and magnet.
About this time I figured that I'd just have to reassemble everything until I could find some replacement parts in a salvage yard. When it came to putting the jackscrew assembly together, I decided to leave the broken portion of the magnet out. At least it would get one pulse per revolution.
As I was putting things back together, I noted that I could have disassembled the jackscrew servo without removing the seat by simply removing the three screws that bolted the drive assembly to the jackscrew. This would come in handy when I got the replacement parts.
After putting everything back, I powered back up and reset the settings. The seat moved in all directions without the grinding and even memorized the #1 drivers position. But when I removed the key, the seat and steering wheel did not retract. It was getting late, so I just left it that way.
This morning I ran down to Wally World to pick a newspaper and while there I set both the #1 and #2 driver position. Voila, the seat and wheel began retracting and it now doesn't drift off position with each cycle.
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Q451990
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Re: Resolved: F50 driver's seat removal for autoposition err
Awesome write-up! I am guessing you have some professional or semi-professional experience with DC motors and their control?
Heath
Heath
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djwarner
- Posts: 407
- Joined: Sat Jan 23, 2010 6:07 pm
- Car: 1971 240Z Series I
2006 350Z - Location: Central Florida
Re: Resolved: F50 driver's seat removal for autoposition err
In another life I was a USAF autopilot technician.
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elwesso
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2007 BMW M Coupe
2007 Infiniti G35 S 6MT - Location: Indiana
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Re: Resolved: F50 driver's seat removal for autoposition err
Great information! Thanks for reporting back... I was waiting to hear of some trickery you used from a motor out of like an old can opener or something... 
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djwarner
- Posts: 407
- Joined: Sat Jan 23, 2010 6:07 pm
- Car: 1971 240Z Series I
2006 350Z - Location: Central Florida
Re: Resolved: F50 driver's seat removal for autoposition err
On reflection, when the ring magnet cracked, it opened up a gap on one split while maintining intimate contact on the other. Apparently, this caused the differing number of pulses when turning clockwise compared to counter-clockwise. I've seen weirder stuff but its been a while.